Open comparative trial of formestane versus megestrol acetate in postmenopausal patients with advanced breast cancer previously treated with tamoxifen

The aim of the trial was to compare efficacy and safety of the aromatase in hibitor formestane (250 mg i.m. given every 2 weeks) with the progestin meg estrol acetate (160 mg administered orally once daily), as second-line ther apy in postmenopausal patients with advanced breast cancer previously treat ed with tamoxifen. A total of 547 patients were enrolled. Analyses revealed no statistically significant or clinically relevant difference between tre atments with respect to time endpoints. In the intent-to-treat analysis, th e median values for time to failure and overall survival for formestane wer e 169 and 561 days, respectively. The corresponding values for megestrol ac etate were 169 days and 597 days, respectively. Overall response rates were comparable for formestane and megestrol acetate (16.3% vs 20.3%). Formestane was better tolerated than megestrol acetate. In the megestrol ac etate group, cardiovascular events, weight increase, and vaginal haemorrhag e were significantly more frequent than in the formestane group. Thus, form estane is a suitable alternative to progestins in patients previously treat ed with tamoxifen. (C) 2000 Harcourt Publishers Ltd.